through synergistic Pd/Cu-catalyzed dynamic kinetic asymmetricallenylation with racemic allenylic esters. The protocol is suitable for a wide range of substrates including the challenging allenylic esters with less sterically bulky substituents and provided chiral allenylic products bearing 1,3-nonadjacent stereocenters with high levels of enantio- and diastereoselectivities (up to >20:1 dr and >99% ee)
Chromium(0)-Promoted [6π + 2π] Cycloadditions of Allenes with Cycloheptatriene
作者:James H. Rigby、Stéphane B. Laurent、Zeeshan Kamal、Mary Jane Heeg
DOI:10.1021/ol802401a
日期:2008.12.18
Photoinitiated [6pi + 2pi] cycloadditions of allenes with (eta(6)-cycloheptatriene)tricarbonylchromium(0) (1) are described. An example of asymmetric induction obtained by reaction of 1 with a chiral 1,3-disubstituted allene is also reported.